1. Field of the Invention
The present invention generally relates to a vehicle door reinforcement. More specifically, the present invention relates to a vehicle door reinforcement that is configured to reduce the effect of shear force in the outer door panel that is generated during movement of the vehicle door between open and closed positions.
2. Background Information
Certain vehicles such as passenger vans, cargo vans and the like often include a sliding vehicle door located on a side of the vehicle. A sliding vehicle door typically slides backward toward the rear of the vehicle to an open position to allow access to the passenger compartment of the vehicle, and forward toward the front of the vehicle to a closed position. Also, a sliding vehicle door usually includes outer and inner door panels. The outer and inner door panels are typically made of sheet metal or other suitable material, and are coupled together by, for example, welding or other types of fasteners such as screws, bolts, rivets and so on. Often, the front edge of the outer door panel is bent about a parting radius toward the inner door panel, and then bent forward about another radius to form a hem flange where the outer and inner door panels are mated together by welding or any other suitable type of fasteners. The parting edge radius is usually small, for example, at or about 2.0 mm to improve fit and finish of the outer door panel with the vehicle body structure when the sliding vehicle door is in the closed position.
As a sliding vehicle door is slid from the open position toward the closed position and slammed closed, a shear force or stress is generated in the outer door panel. The parting edge radius thus bears inertial loads of the outer door panel during a slam close operation. For instance, the shear force or stress in the outer door panel also generates a bending moment about the parting radius due to the step-shaped configuration of the front edge of the outer door panel. As a result of this bending moment, fatigue cracks can form in the outer door panel near the hem flange or near a location at which an outer door handle is typically installed on the outer door panel.
In order to maintain an acceptable outside appearance, welding or other rigid attachment methods are generally not used on portions of the outer door panel that are visible from outside the vehicle. Welding is also not used on the inner surface of such portions of the outer door panel, since the welded areas even on the inner surface can still diminish the appearance of the outer surface of the outer door panel. Hence, to reinforce the outer door panel, a stiffener can be attached to the inner surface of the outer door panel by a low stiffness adhesive such as a mastic adhesive. Also, bake-on composite layer stiffeners can be applied to the hidden inner surfaces of the outer door panel. However, the stiffeners attached with mastic adhesive or with bake-on composite generally do not reduce the stress that occurs at the parting radius as discussed above. For example, bake-on stiffeners of a sufficient thickness typically cannot conform around a small dimension radius, such as the parting radius, to provide adequate reinforcement. Also, mastic adhesive typically does not provide a rigid enough connection to transfer the load away from the parting radius.